1. Field of the Invention
The present invention relates generally to dual stripe magnetoresistive (DSMR) sensor elements employed in dual stripe magnetoresistive (DSMR) read-write heads for magnetic data storage and retrieval. More particularly, the present invention relates to a method for forming a self-aligned dual stripe magnetoresistive (DSMR) sensor element employed within a dual stripe magnetoresistive (DSMR) read-write head for magnetic data storage and retrieval.
2. Description of the Related Art
The recent and continuing advances in computer and information technology have been made possible not only by the correlating advances in the functionality, reliability and speed of semiconductor integrated circuits, but also by the correlating advances in storage density of direct access storage devices (DASDs) employed in digitally encoded magnetic data storage and retrieval. Storage density of direct access storage devices (DASDs) is typically measured as areal storage density of a magnetic data storage medium formed upon a rotating magnetic data storage disk within a direct access storage device (DASD) enclosure. The areal storage density is defined largely by the track width, the track spacing and the linear magnetic domain density within the magnetic data storage medium. The track width, the track spacing and the linear magnetic domain density are in turn determined by several principal factors, including but not limited to: (1) the magnetic read-write characteristics of a magnetic read-write head employed in reading and writing digitally encoded magnetic data into and from the magnetic data storage medium; (2) the magnetic domain characteristics of the magnetic data storage medium which is formed upon the rotating magnetic data storage disk; and (3) the separation distance of the magnetic read-write head from the rotating magnetic data storage disk.
With regard to magnetic read-write heads employed in reading and writing digitally encoded magnetic data into and from a magnetic data storage disk, it has become common in the art to employ magnetoresistive (MR) sensor elements, and in particular dual stripe magnetoresistive (DSMR) sensor elements, as read elements within those magnetic read-write heads since magnetoresistive (MR) sensor elements, and in particular dual stripe magnetoresistive (DSMR) sensor elements, provide high output digital signals, with good linear resolution, independent of the relative velocity of a magnetic data storage medium with respect to the magnetoresistive (MR) sensor element or the dual stripe magnetoresistive (DSMR) sensor element.
Although dual stripe magnetoresistive (DSMR) read-write heads employing dual stripe magnetoresistive (DSMR) sensor elements have thus become quite common in reading and writing digitally encoded magnetic data into and from magnetic data storage media, dual stripe magnetoresistive (DSMR) read-write heads are not entirely without problems. In particular, it is known in the art that dual stripe magnetoresistive (DSMR) read-write heads of optimal read performance are typically only obtained when there is a matching of electrical and magnetic properties between the two magnetoresistive (MR) layers within the dual-stripe magnetoresistive (DSMR) sensor element from which is formed the dual stripe magnetoresistive (DSMR) read-write head. In general, the factors which affect the matching of the two magnetoresistive (MR) layers within a dual stripe magnetoresistive (DSMR) sensor element include but are not limited to: (1) the physical widths of the two magnetoresistive (MR) layers; (2) the alignment of the two magnetoresistive (MR) layers; (3) the read widths of the two magnetoresistive (MR) layers; (4) the sheet resistances of the two magnetoresistive (MR) layers; and (5) the magnetic properties of the two magnetoresistive (MR) layers. As areal density of digitally encoded magnetic data increases, tolerances within the foregoing factors typically need to be minimized to assure optimal read characteristics of digitally encoded magnetic data read with dual stripe magnetoresistive (DSMR) read-write heads. In particular, it is desired in order to assure optimal read properties of a dual stripe magnetoresistive (DSMR) sensor element to eliminate or minimize the tolerance variations with respect to width and/or alignment between the two magnetoresistive (MR) layers within the dual stripe magnetoresistive (DSMR) sensor element. It is towards that goal that the present invention is directed.
A first object of the present invention is to provide a method for minimizing tolerance variations with respect to the width and/or alignment between the two magnetoresistive (MR) layers within a dual stripe magnetoresistive (DSMR) sensor element.
A second object of the present invention is to provide a method in accord with the first object of the present invention, which method is readily manufacturable.
In accord with the objects of the present invention, there is provided by the present invention a method for minimizing tolerance variations with respect to width and/or alignment between the two magnetoresistive (MR) layers within a dual stripe magnetoresistive (DSMR) sensor element, as well as the dual stripe magnetoresistive (DSMR) sensor element formed through the method. To practice the method of the present invention, there is first provided a substrate having formed thereupon a pair of patterned first conductor lead layers which in turn has formed and aligned thereupon a pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers, where the horizontal separation of the pair of patterned first conductor lead layers and the pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers defines a track width of the substrate. There is then formed upon the substrate layer a blanket first magnetoresistive (MR) layer, where the blanket first magnetoresistive (MR) layer contacts and completely covers the track width of the substrate and contacts and at least partially covers the pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers. There is then formed upon the blanket first magnetoresistive (MR) layer a blanket inter-stripe dielectric layer. There is then formed upon the blanket inter-stripe dielectric layer a blanket second magnetoresistive (MR) layer. There is then formed upon the blanket second magnetoresistive (MR) layer a first lift off stencil. The first lift off stencil comprises: (1) a first etched patterned soluble underlayer; and (2) a first patterned masking layer formed upon and overhanging the first etched patterned soluble underlayer, where the first lift off stencil completely overlaps the track width of the substrate and at least partially overlaps the pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers. There is then employed the first lift off stencil as a first etch mask in forming from the blanket second magnetoresistive (MR) layer, the blanket inter stripe dielectric layer and the blanket first magnetoresistive (MR) layer a patterned second magnetoresistive (MR) layer, a patterned inter stripe dielectric layer and a patterned first magnetoresistive (MR) layer with fully aligned edges. There is then employed the first lift off stencil as a first lift off mask to form a patterned dielectric layer over the substrate, where the patterned dielectric layer covers the fully aligned edges of the patterned second magnetoresistive (MR) layer, the patterned inter stripe dielectric layer and the patterned first magnetoresistive (MR) layer. There is then removed the first lift off stencil from the patterned second magnetoresistive (MR) layer. There is then formed a second lift off stencil upon the patterned second magnetoresistive (MR) layer. The second lift off stencil comprises: (1) a second etched patterned soluble underlayer; and (2) a second patterned mask layer formed upon and overhanging the second etched patterned soluble underlayer, where the width of the second lift off stencil is substantially equal to and substantially centered within the track width of the substrate. The second lift-off stencil is then employed as a second lift off mask in forming upon the patterned second magnetoresistive (MR) layer a pair of patterned second anti-ferromagnetic longitudinal magnetic biasing layers having formed and aligned thereupon a pair of patterned second conductor lead layers. After forming upon the patterned second magnetoresistive (MR) layer the pair of patterned second longitudinal magnetic biasing layers having formed and aligned thereupon the pair of patterned second conductor lead layers, the second lift off stencil is removed from the patterned second magnetoresistive (MR) layer.
A second embodiment of the present invention employs a third lift off stencil as a third etch mask for trimming and aligning mis-aligned portions of: (1) a patterned first magnetoresistive (MR) layer having formed thereupon a pair of patterned first conductor lead layers; and (2) a patterned second magnetoresistive (MR) layer having formed thereupon a pair of patterned second conductor lead layers, within a dual stripe magnetoresistive (DSMR) sensor element, where: (1) the patterned first magnetoresistive (MR) layer is separated from the patterned second magnetoresistive (MR) layer by an inter stripe dielectric layer; and (2) the mis-aligned portions of the patterned first magnetoresistive (MR) layer and the patterned second magnetoresistive (MR) layer are trimmed and aligned on the side of the dual stripe magnetoresistive (DSMR) sensor element opposite the air bearing surface (ABS) side of the dual stripe magnetoresistive (DSMR) sensor element. The third lift off stencil is then employed as a third lift off mask in backfilling with a patterned dielectric layer the exposed edges of the trimmed patterned first magnetoresistive (MR) layer and the trimmed patterned second magnetoresistive (MR) layer.
There is provided by the present invention a method for minimizing tolerance variations with respect to the width and/or alignment between the two magnetoresistive (MR) layers within a dual stripe magnetoresistive (DSMR) sensor element. The first embodiment of the method of the present invention achieves this goal through sequentially patterning, while employing a first lift off stencil as a first etch mask, a blanket second magnetoresistive (MR) layer, a blanket inter stripe dielectric layer and a blanket first magnetoresistive (MR) layer to form a patterned second magnetoresistive (MR) layer, a patterned inter stripe dielectric layer and a patterned first magnetoresistive (MR) layer with fully aligned edges, while subsequently employing the first lift off stencil as a first lift off mask in forming a patterned dielectric layer which covers the fully aligned edges of the patterned second magnetoresistive (MR), the patterned inter stripe dielectric layer and the patterned first magnetoresistive (MR) layer formed from the corresponding blanket layers. The second embodiment of the method of the present invention achieves this goal through trimming, while employing a third lift off stencil as a third etch mask, mis-aligned portions of: (1) a patterned first magnetoresistive (MR) layer having formed thereupon a pair of patterned first conductor lead layers; and (2) a patterned second magnetoresistive (MR) layer having formed thereupon a pair of patterned second conductor lead layers, where: (1) the patterned first magnetoresistive (MR) layer is separated from the patterned second magnetoresistive (MR) layer by an inter stripe dielectric layer; and (2) the mis-aligned portions of the patterned first magnetoresistive (MR) layer and the patterned second magnetoresistive (MR) layer are trimmed and aligned on the side of a dual stripe magnetoresistive (DSMR) sensor element opposite the air bearing surface (ABS) side of the dual stripe magnetoresistive (DSMR) sensor element.
The method of the present invention is readily manufacturable. The first embodiment of the method of the present invention provides a novel ordering of dual stripe magnetoresistive (DSMR) sensor element fabrication processes generally known in the art of dual stripe magnetoresistive sensor (DSMR) sensor element fabrication. Both the first embodiment of the method of the present invention and the second embodiment of the method of the present invention employ lift off stencils sequentially as: (1) etch masks for forming at least partially aligned magnetoresistive (MR) layers within dual stripe magnetoresistive (DSMR) sensor elements; and (2) lift off masks for forming patterned insulator layers covering the edges of the aligned magnetoresistive (MR) layers within the dual stripe magnetoresistive (DSMR) sensor elements. Since methods and materials through which lift off stencils may be formed are similarly generally known in the art of dual stripe magnetoresistive (DSMR) sensor element fabrication, the first embodiment of the method of the present invention and the second embodiment of the method of the present invention are readily manufacturable.